Cartridge actuated tools

ABSTRACT

A cartridge actuated tool, in which a tool-head is operated by movement of a piston within a gas-tight pressure chamber under the action of gas pressure produced by the firing of a cartridge, incorporates valve means inoperable before release of the trigger by which the gas can be retained within the pressure chamber until cooling reduces the pressure sufficiently to permit comparatively noiseless exhaust of gas from the pressure chamber.

D United States Patent 1191 1111 3,805,516 Eastham et al. Apr. 23, 1974[5 CARTRIDGE ACTUATED TOOLS 2,204,308 6/1940 l-lerzmark 60/261 x 4 [75]Inventors: Gerard Eastham, Chorley; Thomas v 23:22a H Gordon smithAllbwme, both of 3,540,141 11/1970 Butler 1' x England 7 3,686,8588/1972 Termet 60/26 1 X [73] Assignee: The Secretary of State forDefense in Her Britannic Majesty? Primary Examiner-Wendell E. BurnsGovernment of the Umted Kmgdom Attorney, Agent, or Firm-Stevens, Davis,Miller & of Great Britain and Northern Mosher Ireland, London, England22 Filed: Jan. 21, 1972 12 1 App1- 19 78 57 ABSTRACT A cartridgeactuated tool, in which a tool-head is op- [301 Forelgn Apphcation'Priority Data erated by movement of a piston within a gas-tight Jan. 21,I971 Great Britain 2900/71 pressure chamber under the action of gaspressure produced by the firing of a cartridge, incorporates 52valvermeans ill-operable before release of the trigger Int. Cl. the gcan be retained within the pressure of Search chamber until coolingreduces the pressure sufficiently to ermit com arativel noiselessexhaust of gas from [56] References Cned. the pressure clfamber. y

UNITED STATES PATENTS 1,915,435 6/1933 Miller 60/26.l x V 10 Claims, 3Drawing Figures 7 3 4 2 9 3 IO 6 l4 /I am \L/ 1 1 1 1 1 34 I 1 11 as 1 I1 3a 111,

2, 1 \g L, w I 23 .1 s V 2O s I 40 PATENTEDAPR 23 mm 38055165 SHEET 2 BF3 FIG.2.

PATENTEDAPR 23 1974 SHEET3UF 3 3805516 FIG. 3.

1 CARTRIDGE ACTUATED TOOLS This invention relates to cartridge actuatedtools, and in particular to tools which are capable of producing a highpressure sustained for a sufficiently long period of time to permit theassociated use of a crimping or like tool.

The invention comprises a cartridge actuated tool wherein gas producedby the cartridge when fired is confined within a substantially gas-tightchamber, and which gas generates pressure required to operate a toolhead attached to or forming part of the tool; and means for releasingsaid gas pressure after a suitable delay.

By this latter means the gas can be retained within the chamber untilthe gas, initially at a very high temperature following the firing ofthe cartridge, has cooled sufficiently to cause the pressure to fall tosuch an extent. that the exhaust gas escapes at a sub-sonic velocity,and the resultant absence of a-shock wave en'- sures that the tool isrelatively silent in operation. In practice, it has been found that thetime needed for the gas to remain in the chamber is shorter than thetime of an operators action in actuating and releasing a firingmechanism, so that the speed of operation of the tool need not besignificantly reduced.

The type of cartridge employed will depend on the size of tool, and theuse to which the tool is being put, but when used in conjunction with acrimping t'ool head it has been found preferable to employ a relativelyslow burning cartridge, so that the pressure imparted by the tool headincreases steadily for a time perhaps of the order of a tenth of asecondsufficient to allow plastic flow to take place in the materialbeing worked upon. When used to join aluminium electric powerconductors, a greatly improved electrical contact has resulted whenplastic flow has taken place within the conductors.

The invention can take many forms, one of which is a breech and stocksimilar in appearance to, a pistol, in which the cartridge, in a' sealedchamber as hereinbefore described, is fired as a result of a triggerbeing pressed: the gas maythenbe released, for example, as a result ofthe release of the trigger. In this way, the tool is completelyindependent of an external power source, although an arrangement wherebythe cartridge is'activated by an electrically fired cap or other meansmay be used, as in any other form of the invention.

By way of example, particular embodiments of the invention will now bedescribed with reference to the accompanying drawings, where:

FIG. 1 is a view of the underside of a tool,

FIG. 2 is a section on the line II II of FIG. I, and

FIG. 3 is a section similar to that of FIG. 2 of a'modified toolincorporating alternative exhaust and firing arrangements. 7

Each embodiment described takes the form of a breech, stock and triggermechanism similar in appearance to a pistol, adapted to be used forcrimping cable terminations and jointing sleeves to aluminiumconductors, and is shown fitted for this purpose at its forward end to atypical G-type crimping head 1 into whicha die is fitted. I

Referringto FIGS. 1 and 2, the breech body 2 comprises a pressurechamber 3, within which is locateda piston 4, and a cartridge holder 5,in which a cartridge 6 may be inserted. The piston 4 is normallyretained in 2 its rearrnost position by means of a compression spring 7and retaining collar 8, which allows the desired forward movement of thepiston.

One or more piston rings 9 fitted to the piston may be made of anysuitable material such as a PTFE- Bronze combination or syntheticrubber, according to the application.

The cartridge holder 5 is fitted with a grid 10 which prevents the mainpropellant charge from leaving the cartridge case when the end closuredisc of the cartridge becomes consumed, and ensures the required burningrate of the propellant and generation of gas pressure.

It is necessary to make provision for the loading and unloading of acartridge and for removing the cartridge holder for cleaning. For thispurpose, the breech body 2 is adjoined to the stock 11 by a pivot screw12, which allows the stock 11 to be pivoted away from the breech body 2thus exposing the cartridge holder 5. Means are provided for holding thebreech body 2 and stock 11' together in position while firing, saidmeans comprising a locking latch 13, held in the locked position by acompression spring I4, housed in the upper section of the breech body 2and engaging in a hole 15 in the upper part of the stock 11.

Gas venting mechanism is provided in the breech body 2, whereby gas isreleased to atmosphere from the pressure chamber 3, first through a venthole 16 positioned at the rear of the pressure chamber and thence via asmall valve orifice 17 which is opened and closed by movement of aplunger 18, located in a small bore 19 beneath the pressure chamber 3,its closure being induced, against the action of a valve spring 20, bythe firing movement of the trigger 21. Provision may be made whereby thegas can be piped away from the operator upon emerging from the valveorifice 17 at' the side of the breech body 2.

A flat 22in the side of the plunger 18 locates against one endof thetrigger 21 so that, as the trigger is pulled to fire the cartridge 6,the plunger 18 moves forward against the action of the valve spring 20and blanks off the valve orifice 17, thus sealing the pressure chamber31 When the trigger is released after the cartridge'has fired, theplunger 18" moves back and releases the gas. Arr operators normal actionproduces a sufficient delay to enable the operation to be completedwithout the production of explosive noise, although the operator cancontinue to press the trigger if he so desires, to ensure a much lowerresidual pressure in the system at the instant of release.

In the event of the plunger 18 sticking in the closed position, due, forexample, to a build-up of deposits, means are provided whereby theplunger 18 can be released, said means comprising a small cam plate23and an operating'handle 24. By rotation through l from the normaloperating position, the cam plate 23'may be used to move the plunger 18to or maintain it inthe valve-open position and can therefore also beemployed to prevent any movement of the trigger 21 and thus to act asasafety catch.

In the released position, the trigger 21, mounted in the stock 11 of thetool and protected by a trigger guard 25, rests against a stop 26 alsomounted in the stock 11. As the trigger is pulled back, it pushes afiring plunger 27 through a small free movement to contact a hammerrelease rod 28 which on further movement of the trigger 21 actuates ahammer 29 via a sear 30.

The purpose of the said small free movement is to ensure that the valveorifice 17 is closed before the cartridge is fired. When the trigger isin the released position, the firing plunger 27 is held against thetrigger and clear of the hammer release rod 28 by a return spring 31.

The cartridge 6 is ignited by a percussion cap, which is itself ignitedwhen hit by a striker 32, mounted in the stock 1 1 directly behind thecartridge case and retained in its bore by a retaining pin 33. Thestriker 32 is normally held back from the cartridge cap by a smallstriker return spring 34 and only strikes the cap when hit by the hammer29.

The hammer 29 is mounted alongside a hammer plate 35 on the same pivotpin 36, and the hammer and hammer plate are interconnected by a hammerpin 37 set in the hammer 29 and protruding into a hole 38 of largerdiameter than itself in the hammer plate 35, this arrangement permittinga small rotary movement of the hammer relative to the hammer plate. Whenfree, the hammer plate 35 is held in an upright rest position againstthe stock by a torsion spring 39, whilst at the same time the hammer 29is held in contact with the striker 32 without forcing the strikerforward.

However, when the hammer 29 and hammer plate 35 are pulled back andsuddently released momentum carries the hammer 29 additionally forwardbeyond the aforesaid rest position through the small movement permittedrelative to the hammer plate 35 and forces the striker 32 on to thepercussion cap to ignite the cartridge 6. When the hammer plate 35 andhammer 29 are pulled back to their extreme position, the hammer plateengages with the sear 30, which is mounted on a sear pivot pin 40 andheld in engagement with a detent 41 on the hammer plate 35 by a torsionspring 42.

The sear 30 is also pivotally connected to the hammer release rod 28, sothat when the trigger 21 is pressed to move back the hammer release rod28, the sear 30 is rotated about the sear pivot pin 40 and moved out ofengagement with the detent 41 resulting in firing of the cartridge.

Reference is now made to FIG. 3 which shows a modified arrangement.

To reduce the stress on the pivotal connection 46 between the stock 11aand the breech body 2a, the cartridge holder a is screwed into thebreech body, so that when a cartridge 6a is fired the consequentreaction is restricted to the area of the cartridge. To provideadditional support, the stock 11a has a portion 47 which engages with arecess 48 in the breech body 211.

To facilitate the removal of a spent cartridge from the cartridge holder5a, the pivotal connection 46 between the stock and breech body ispositioned away from the centre axis of the tool, we that on beingpivoted the stock moves initially away from the breech body. Aring-shaped extractor 49 surrounding the exposed end of the cartridgecan be withdrawn by hand to extract the cartridge from the cartridgeholder.

The gases resulting from the firing of the cartridge 6a exhaust toatmosphere through a vent-hole 16a and an axially symmetrical exhaustchamber 50 having a small orifice 51 in its wall. A sealing plug 52 iscontained in the exhaust chamber, held in place by being screwed in aboss 53. The sealing plug 52 incorporates at one end a circular seal 54and at the other end a handle 55, rotation of which causes the sealingplug 52 to move axially within the chamber 50. When the sealing plug 52is at one end of its axial movement the circular seal 54 abuts againstan end of the exhaust chamber preventing passage of gas through thevent-hole 16a, in which position a recess 56 in the sealing plug 52 isaligned with a bore 5a in the breech body, in which a safety rod 58 isslidably mounted. The safety rod 58 is spring-loaded to abut against aprojection 59 of the trigger 21a, and the trigger can only be pressed ifthe rod can move into the recess 56 in the sealing plug 52, ie if thesealing plug 52 is in the position preventing the exhaust gases fromescaping. After firing, the exhaust gases are released, subsequent torelease of the trigger, by manual rotation of the handle 55, causing thesealing plug 52 to move axially and permit the exhaust gases to passthrough the orifice 51.

The firing mechanism operates as follows: a sear 60, retained by a searpin 61 locating in a recess 62 in the sear, is pivotally connected tothe trigger 21a and urges by a spring 63 against a hammer 64. As thetrigger 21a is pulled, the sear 60 moves upwards, pushing the hammer 64back against the action of a hammer spring 65 until a projection 66 onthe sear 60 abuts a striker 32a. At this position, the sear 60 andhammer 64 come out of engagement permitting the hammer 64 to comeforward under the action of the hammer spring 65 and strike the searprojection 66, forcing the-striker 32a on to the percussion cap toignite the cartridge 6a.

It will be seen that thetwo embodiments described differ in certainother minor features, which do not however alter the mode of operation,and it will be clear that the different piston, exhaust and firingarrangements are independent of one another, so that, for example, theexhaust arrangement of one embodiment may be used with the firingarrangement of the other whilst remaining within the scope of theinvention.

We claim:

1. A cartridge actuated tool incorporating a toolhead, a substantiallygas-tight pressure chamber, an actuating piston slidable within thepressure chamber for operating the tool-head and actuated by gaspressure produced by firing of a cartridge, firing means for firing thecartridge, a trigger for operating the firing means, a valve throughwhich the gas can be exhausted, closure means for the valve and meanscooperating with the trigger for preventing the valve from opening untilthe trigger is released.

2. A cartridge actuated tool as claimed in claim 1 in which the meanscooperating with the trigger comprises a rod movable by the triggeragainst the action of a return spring, which rod maintains the closuremeans in the valve closed position while the trigger is held in thepulled position.

3. A cartridge actuated tool as claimed in claim 2 in which the valveclosure means comprises a valve piston attached to and movable with therod which valve piston closes a vent-hole in the pressure chamber whenthe trigger is in the pulled position.

4. A cartridge actuated tool as claimed in claim 3 in which the valvecomprises a cylinder within which the valve piston is slidable and withwhich the vent-hole communicates and in whose wall is an orifice open toatmosphere, the valve piston being movable from a position in whichexhaust gas can pass from the vent-hole to the orifice to a positionpreventing the said passage of exhaust gas.

5. A cartridge actuated tool as claimed in claim 2 incorporating a stopdevice by which the rod can be engaged to retain the tool in thevalve-open position.

6. A cartridge actuated tool as claimed in claim 5 in which the stopdevice incorporates a cam which is arranged to engage the rod and returnit to the valveopen position in the event of the return spring failingto operate.

7. A cartridge actuated tool as claimed in claim 2 in which the valveincorporates a chamber and sealing means movable within the chamber andoperable manually to open and close the valve.

8. A cartridge actuated tool as claimed in claim 7 in which the sealingmeans has a recess which is aligned with the rod when the valve is inthe closed position, whereby the rod engages in the recess when thetrigger is pulled to prevent opening of the valve before release of thetrigger.

9. A cartridge actuated tool as claimed in claim 1 in which the firingmeans incorporates a striker and a spring-loaded hammer operable onpulling the trigger for actuating the striker.

\ 10. A cartridge actuated tool as claimed in claim 9 incorporating asear pivoted to and movable by the trigger to engage and raise thehammer, which is released by disengagement of the sear and which isspaced from the striker, the sear being movable during operation of thehammer into the space between the hammer and the striker, whereby ondisengagement of the sear from the hammer the hammer strikes the sear toactuate the striker.

1. A cartridge actuated tool incorporating a tool-head, a substantiallygas-tight pressure chamber, an actuating piston slidable within thepressure chamber for operating the tool-head and actuated by gaspressure produced by firing of a cartridge, firing means for firing thecartridge, a trigger for operating the firing means, a valve throughwhich the gas can be exhausted, closure means for the valve and meanscooperating with the trigger for preventing the valve from opening untilthe trigger is released.
 2. A cartridge actuated tool as claimed inclaim 1 in which the means cooperating with the trigger comprises a rodmovable by the trigger against the action of a return spring, which rodmaintains the closure means in the valve closed position while thetrigger is held in the pulled position.
 3. A cartridge actuated tool asclaimed in claim 2 in which the valve closure means comprises a valvepiston attached to and movable with the rod which valve piston closes avent-hole in the pressure chamber when the trigger is in the pulledposition.
 4. A cartridge actuated tool as claimed in claim 3 in whichthe valve comprises a cylinder within which the valve piston is slidableand with which the vent-hole communicates and in whose wall is anorifice open to atmosphere, the valve piston being movable from aposition in which exhaust gas can pass from the vent-hole to the orificeto a position preventing the said passage of exhaust gas.
 5. A cartridgeactuated tool as claimed in claim 2 incorporating a stop device by whichthe rod can be engaged to retain the tool in the valve-open position. 6.A cartridge actuated tool as claimed in claim 5 in which the stop deviceincorporates a cam which is arranged to engage the rod and return it tothe valve-open position in the event of the return spring failing tooperate.
 7. A cartridge actuated tool as claimed in claim 2 in which thevalve incorporates a chamber and sealing means movable within thechamber and operable manually to open and close the valve.
 8. Acartridge actuated tool as claimed in claim 7 in which the sealing meanshas a recess which is aligned with the rod when the valve is in theclosed position, whereby the rod engages in the recess when the triggeris pulled to prevent opening of the valve before release of the trigger.9. A cartridge actuated tool as claimed in claim 1 in which the firingmeans incorporates a striker and a spring-loaded hammer operable onpulling the trigger for actuating the striker.
 10. A cartridge actuatedtool as claimed in claim 9 incorporating a sear pivoted to and movableby the trigger to engage and raise the hammer, which is released bydisengagement of the sear and which is spaced from the striker, the searbeing movable during operation of the hammer into the space between thehammer and the striker, whereby on disengagement of the sear from thehammer the hammer strikes the sear to actuate the striker.